This invention relates generally to lasers, and more particularly to Nd:YAG lasers.
A large number of different kinds of solid lasers have been discovered, distinguished from one another by host material, by active lasing ions with which the host is doped, and by output characteristics. Of these, mainly ruby, Nd:YAG and Nd-doped glass laser systems are of major importance in industrial and laboratory environments. They are particularly useful for materials processing applications which include drilling, welding, cutting and scribing.
A wide variety of Nd:YAG lasers and industrial systems are currently manufactured. Their usefulness and versatility is due in part to the fact that they can be operated in a number of different modes.
However, Nd:YAG lasers have proved to be relatively inefficient and have relatively short lifetimes due to limitations of their pumping sources which are typically arc or incandescent lamps, or light-emitting diodes.
Pumping by arc or incandescent lamps is undesirable due to limited lifetimes. The lamps themselves have lifetimes of a few hundred hours and need periodic replacement. Moreover, they generate unnecessary and damaging ultraviolet radiation which tends to degrade the YAG material itself.
Pumping by light-emitting diodes is undesirable because of limited power and focusability and low efficiency. The wavelength of the emitted light is very broad and does not match the Nd:YAG absorption line. Additionally, light-emitting diodes have a broad emission spectrum which provides inherent limitations when they are utilized as pumping sources for Nd:YAG lasers.
Exemplary Nd:YAG lasers pumped by these sources are disclosed by: F. W. Ostermayer, Jr., Appl. Phys. Lett., Vol. 18, No. 3 (1971) p. 93; N. P. Barnes, J. Appl. Physics, Vol. 44, No. 1 (1973) p. 230; R. B. Chesler and D. A. Draegert, Appl. Phys. Lett., Vol. 23, No. 5 (1973) p. 235; R. B. Allen and S. J. Scalise, Appl. Phys. Lett., Vol. 14, No. 6 (1969) p. 188; and W. Culshaw, J. Kanneland and J. E. Peterson, J. Quart. Elect., Vol. QE-10, No. 2 (1974) p. 253.
However, there exists a need for a more efficient, longer life Nd:YAG laser for low to high power applications. A need also exists for a frequency-doubled Nd:YAG laser which has a long lifetime, is efficient and suitable for applications in the visible light range as well as other wavelengths.